1. Field of the Invention
This disclosure relates in general to a landing system for aircraft, and more particularly to a retractable air cushion landing system for aircraft.
2. Description of the Prior Art
It is already known in the prior art to provide a cushioned landing system for certain aircraft using inflatable air bags. Present air cushion landing system concepts consist of providing an air bag shaped like an elongated donut. This air bag is commonly called the trunk. The trunk of the air cushioned landing system is usually inflated and provides a skirt to contain air pressure between the ground and the aircraft fuselage. The trunk also functions to attenuate landing impact of the aircraft at the time of touchdown.
The main difficulty with the above described system which includes an impact absorbing trunk concerns retraction of the trunk after takeoff of the aircraft.
For remotely piloted vehicles, the problem has been avoided by utilizing two trunks -- one for takeoff, and an alternate or spare trunk for recovery of the aircraft. In this dual trunk system, a remotely piloted vehicle will lift off with the recovery trunk folded and stored in a bag beneath the takeoff trunk. After lift off, the takeoff trunk is dropped from the aircraft. When the remotely piloted vehicle lands, the recovery trunk is inflated from engine bleed air lines, and "pops out" of the bag which had previously contained it during takeoff and cruise. After landing is accomplished, the recovery trunk is replaced by hand folding. The present invention concerns a novel system which facilitates retraction of the air cushion bags and has other advantages that will be apparent forthwith.
Other attempts to solve the problem of retraction of the air cushion landing system includes using an elastic trunk. The purpose in using an elastic trunk is to facilitate storing of the trunk when it is not in use. When the trunk is not in use it remains unpressurized and deflated, and is contracted against the fuselage of the aircraft. Many difficulties arise, however, from the use of elastic trunks. The elastic trunks are relatively expensive and also cause various dynamic problems during operation of the aircraft.
Other retraction systems in the prior art for retracting the trunk portion of an air cushion landing system require a large volume for trunk storage and involve a complex web of cables and pulleys for retraction.
A novelty search of the prior art relating to air cushion landing systems discovered the following U.S. Patents:
______________________________________ U.S. Patent No. Classification Inventor ______________________________________ 2,944,771 244/100 O. J. Bush 3,258,080 180/127 G.H. Williams, et.al. 3,297,280 180/116 Shao-Tang LEE 3,384,197 180/117 A.E. Bingham, et.al. 3,802,602 244/100 F.W. Wilson 3,826,449 244/100 Nelson, et.al. 3,865,332 244/100 A.V. Coles 3,869,103 180/124 Nelson, et.al. Also, one British patent was discovered: BR 1,089,464 180/127 Rowland Hunt ______________________________________
A close approach to the proposed construction of the present invention was not observed in the above cited patents. Perhaps of most merit are U.S. Pat. Nos. 3,869,103, 3,258,080 and British Pat. No. 1,089,464. U.S. Pat. No. 3,869,103 describes a system for retracting the "elongated donut" trunk. This system, however, requires a relatively complex array of cables and pulleys which are not needed in the present invention. U.S. Pat. No. 3,258,080 and British Pat. No. 1,089,464 show rigid pivoted structures and air bag means employed in various arrangements. In these patents, however, the simplicity and effectiveness inherent in the present invention is lacking.